<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>面积</title>
</head>
<body>
    <script>
        function area(radius) {
            var result=parseInt(radius)*parseInt(radius)*3.14
            alert("圆的面积是"+result)
        }
        var radius=prompt("请输入半径","");
        area(radius);
    </script>
</body>
</html>